DVDs become common as optical discs onto which various information is recorded, such as content information, which is video information, audio information, sub-picture information, or the like, and reproduction control information and so on. According to a DVD standard, the video information (video data), the audio information (audio data) and the sub-picture information (sub-picture data) are packetized each with the reproduction control information (navigation data), and are multiplexed and recorded onto a disc in a program stream format of MPEG 2 (Moving Picture Experts Group phase 2), which is a high performance encoding technology. Among them, the video information has data, which is compressed in a MPEG video format (ISO 13818-2), by one stream in one program stream. On the other hand, the audio information is recorded in a plurality of formats (i.e. linear PCM, AC-3, MPEG audio and so on) and has data for up to 8 streams in one program stream. The sub-picture information is defined by a bitmap, and is compressed and recorded in a run length method, and has data for up to 32 streams in one program stream.
In the case of the DVD, as described above, a plurality of streams of the selectable audio information (e.g. streams of a stereo sound, a surrounding sound, an original English sound, a dubbed Japanese sound, and the like) and a plurality of streams of the selectable sub picture information (e.g. streams of Japanese subtitle, English subtitle, and the like) are multiplexed and recorded, by using the program stream format, with respect to one stream of the video information in one movie or film, for example.
On the other hand, a transport stream format of MPEG2 standard has been recently standardized, which is suitable for larger-capacity and higher-speed data transfer. According to the transport stream format, a plurality of elementary streams are transferred at the same time at a much higher transfer speed than that of the above-mentioned program stream format. For example, a plurality of programs, such as a plurality of satellite digital broadcasting TV channels in one satellite radio wave, are transmitted at the same time in a TDM (Time Division Multiplex) scheme. Namely, in the transport stream format, a plurality of elementary streams of the video, each having a large data amount, can be time-division-multiplexed and transmitted at the same time. For example, a plurality of movies recorded on a plurality of DVDs can be transmitted at the same time.
Incidentally, in the present application, a signal video stream existing in a stream group which can be multiplexed and recorded and which can be synchronously reproduced, such as the above-mentioned program stream for example, or a situation that there is a single video stream in the stream group, is referred to as a “single video stream” as occasion demands.